Schedule of Purchase Price Allocations Related to Acquisitions (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Business Acquisition [Line Items]
Tax deductible goodwill	$ 0	$ 0	$ 30
Non-tax deductible goodwill	0	395	135
Weighted average lives of finite-lived intangibles (years)	12 years	4 years	5 years
Customer Relationships
Business Acquisition [Line Items]
Identifiable intangible assets (finite-lived)	0	62	28
Weighted average lives of finite-lived intangibles (years)		5 years	5 years
Other
Business Acquisition [Line Items]
Identifiable intangible assets (finite-lived)	$ 3	$ 10	$ 1
Weighted average lives of finite-lived intangibles (years)	12 years	1 year	3 years